Now the secret is out—and distributed. For the more than half a billion iTunes subscribers, the new U2 album will be arriving in their iTunes libraries. But why did U2 decide to release Songs of Innocence in this way?

In the green room after the Apple iPhone 6 and Watch launch at Cupertino’s Flint Center, there were clues. Bono stood with one arm around Apple design honcho Jony Ive—who Bono met in 2004, when U2 collaborated on a special edition (RED) iPod—and another around superstar Australian designer Marc Newson, who Ive recently hired to amp up Apple’s industrial aesthetic. Bono describes the trio as the “three amigos” and compares the budding partnership between Apple’s key designers to the Beatles and the Rolling Stones joining forces. But although the bond between the band and Apple—including ties to Interscope Records chairman Jimmy Iovine, who produced two U2 albums and recently sold his Beats company to Apple—goes back a decade and helped to seal the deal, there were also sound business reasons behind it. And, because Bono is involved, a campaigning zeal too.

“The charts are broken,” he says. The old music industry has reached a low point and hasn’t kept up with the digital world. He wants to see artists’ reach measured by how much they’re listened to, by whatever medium or method.

But releasing the album free to iTunes subscribers does not mean the band has given the album away. “We were paid,” Bono tells TIME. “I don’t believe in free music. Music is a sacrament.”

Amen.

He won’t divulge what Apple shelled out for Songs of Innocence. Whatever the sum, it’s a gift to listeners.